the past, meters of the analog or counting type, as well as indicator lamps, such as, for instance, light bulbs and LEDs, etc., have been often used on the dashboards of motor vehicles and the like. In addition, segmented liquid crystal displays have also been commonly used for numeric digital displays and indicator displays.
It should be noted that, in recent years, liquid crystal panel display devices and other dot-matrix type image display devices have come to be used for the dashboards of motor vehicles, etc. Specifically, at least a portion of a dashboard is formed as a dot-matrix type image display device capable of displaying arbitrary patterns, with images of various indicators and meters, such as a speedometer, etc. displayed thereon.
In this manner, the use of dot-matrix type image display devices on the dashboards of motor vehicles, etc. allows for imparting a variety of patterns to dashboard displays. For example, the types of the displayed meters and indicators, as well as their arrangement and dimensions, can be dynamically changed as needed. Furthermore, images other than the dashboard image, such as, for instance, scenery from outside the vehicle captured by CCD (charged coupling device) imaging devices or images used for navigation, etc. can be composited and displayed together with images of meters.
Thus, in a conventional steerable vehicle information display system utilizing a dot-matrix type image display device, an ECU (electronic control unit) used for image generation collects information transmitted from multiple ECUs provided in various locations onboard a motor vehicle etc. (e.g. information indicating the opened/closed status of the doors, the speed of travel of the motor vehicle, etc.). Multiple images representing the status of the various sections of the motor vehicle, such as, for instance, images of a speedometer, a tachometer, a gear indicator, a coolant temperature gauge, or a fuel level gauge, etc., are then created in the image-generating ECU. The image-generating ECU then composites the multiple created images and forwards them to the image display device, directing it to display the composite image. This makes it possible to display a composite image of the dashboard of the motor vehicle etc.
Incidentally, the problem with conventional steerable vehicle information display systems is that they suffer from display disturbances caused by momentary power interruptions, during which there occurs an instant drop in the battery voltage of the motor vehicle etc.
In other words, the image-generating ECU of the above-described conventional steerable vehicle information display system receives information representative of the status of each section of the motor vehicle from the processors of the ECUs provided in each section. That is to say, information on the RPM of the engine, traveling speed, gear position, etc. is transmitted to the image-generating ECU from the processor of the ECU that governs the drive system, including the engine and the powertrain. In addition, information regarding the illumination status of the lights, the opened/closed status of the doors, the presence or absence of airbag malfunctions, the fastened/unfastened status of the seat belts, etc. is transmitted from the processor of the ECU that governs the safety system used to enhance the safety of the motor vehicle. Furthermore, information on cabin temperature and air conditioner air outlet temperature is transmitted from the processor of the ECU that governs the amenity system used to enhance comfort inside the vehicle.
In the conventional steerable vehicle information display system, the image-generating ECU utilizes the respective information of multiple types transmitted by the multiple ECUs to generate images of predetermined patterns that make it easier for the driver to intuitively recognize the status of the various systems mentioned above. For instance, an image representing a conventional analog type speedometer, or an image displaying the speed as a numeric value is generated in order to represent the speed of travel. Moreover, an image showing that a door is open is generated if a door is not snugly closed. In addition, images are generated that represent various indicators, for instance, such as a gear position indicator, a fuel level gauge, a radiator coolant temperature gauge, etc. Images generated in this manner based on the various types of information are then superimposed to generate a single image representing the entire motor vehicle dashboard, which is displayed on the display device.
In such a conventional construction, some of the multiple ECUs provided in the various sections of the motor vehicle may sometimes be instantly halted if there is a momentary power interruption due to a battery voltage drop. Because in such cases no information is sent from the halted ECUs to the image-generating ECU, the image-generating ECU cannot create the images of the sections corresponding to the halted processors. As a result, at least some of the images supposed to be displayed as components of the motor vehicle dashboard are no longer displayed. For example, if the ECU that governs sensors detecting the traveling speed of the motor vehicle is halted, the image of the speedometer etc. instantly vanishes from the display.
JP H11-53270A is noted to have disclosed a technology for controlling the operation of onboard electrical devices during a momentary power interruption. According to the invention disclosed in JP H11-53270A, in case of a battery voltage drop, a determination is made as to whether this is a momentary power interruption and the operating conditions of the onboard electrical devices at the time of resumption of operation are set depending on whether this was indeed a momentary power interruption.